1. Field of the Invention
The present invention relates to waveguide grating routers, and, in particular, to waveguide grating routers that function as wavelength-dependent splitter/routers.
2. Description of the Related Art
An ideal optical splitter is a device that receives light of a particular wavelength at an input port and splits the power of that light evenly among a number of output ports. An ideal optical router is a device that routes light having different wavelengths from an input port to different output ports, where each output port corresponds to light having a different wavelength.
Optical devices that act as routers in one wavelength band and as splitters in another wavelength band have important applications in optical networks. This functionality is important for optical networks, because it enables the overlaying of a wavelength-division-multiplexed (WDM) network (which relies on routers) with a broadcast type of network (which relies on splitters).
Such devices are called two-PON-in-one devices or splitter/routers, where PON stands for passive optical network. When functioning as an optical splitter, a two-PON-in-one device splits light received at one input port among two or more output ports. When functioning as an optical router, a two-PON-in-one device receives light at one input port and routes light having different wavelengths to different output ports. Such a device may be referred to as a wavelength-dependent splitter/router, because the wavelength ranges of the light energy applied at the input port determine whether the device operates as either a splitter or as a router.